Novel photographic products and processes



. 3,043,689 NOVEL PHOTOGRAPHEC PRODUCTS AND PROCESSES Howard C. Haas, Arlington, Mass, assignor to Polaroid Corporation, Cambridge, Mass, a corporation of Dela= ware No Drawing. Fiied Aug. 22, 1960, Ser. No. 50,847 18 Claims. (Cl. 96-29) This invention relates to photography and more p'articu larly to novel photographic products and processes.

One object of this invention is to provide novel imagereceiving elements for use in color diffusion transfer processes. I

Another object of this invention is to provide novel color diffusion transfer processes utilizing said imagereceiving elements.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description. I g

.The present invention is particularly related to color diffusion transfer processes. In such processes a sheet of photosensitive material is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, an imagewise distribution of color-providing materials is formed. At least a portion of these color-providing materials is transferred by means of an alkaline aqueous processing liquid to a super-posed image-receiving layer to form a color positive image thereon. As examples of such processes, mention may be made of the processes claimed and disclosed in the copending U.S. application of Howard G. Rogers, Serial No. 748,421, filed July 14, 1958, now U.S. Patent 2,983,606, granted May 9, 1961 wherein dye developers (i.e., dyes containing a silver halide developing function and capable of developing a latent silver halide image) are the color-providing materials, the processes claimed and disclosed in U.S. Patent No. 2,647,049, issued July 28, 1953 to Edwin H. Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing materials, and the processes disclosed in U.S. Patent No. 2,774,668, issued December 18, 1956 to Howard G. Rogers, wherein complete, preformed dyes which are capable of coupling are used as the color-providing substances.

The image-receiving elements used in such processes generally comprise an opaque or transparent support coated with an image-receiving layer of a dyeable material which is permeable to the alkaline aqueous processing solution. In the past, it has been proposed to use filmforming materials such as polyvinyl alcohol and nylons such as N-methoxymethyl polyhexamethylene adipamide as the dyeable materials.

T ice Patented July 10, 1962 It has now been discovered that by using an imagereceiving layer comprising an acetal of polyvinyl alcohol and 4-pyridine carboxaldehyde in such processes, transfer images having improved density and enhanced stability in sunlight may be obtained.

The image-receiving elements of this invention are particularly useful in color diffusion transfer processes which employ dye developers. The improvements have been especially marked when azo and anthraquinone dye developers are employed. Dye developers, as noted above, are compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function. They may be further defined as dyes which are capable of developing a silver halide emulsion. By a silver halide developing function is meant a radical capable of developing an exposed silver halide image. Particularly useful dye developers are those in which the silver halide developing function is provided by the presence of a benzenoid developing radical. A preferred benzenoid developing radical in such compounds is a hydroquinonyl radical. Examples of representative dye developers are given in the previously mentioned U.S. application of Howard G. Rogers, Serial No. 748,421. Additional useful dye developers are described in the following copending U.S. applications:

Application Serial No. 612,045, filed September 25, 1956,

in the names of Elkan R. Blout, Milton Green and Howard G. Rogers.

Application Serial No. 612,052, filed September 25, 1956, in the names of Milton Green and Howard G. Rogers.

Application Serial No. 612,053, filed September 25, 1956,

in the name of Myron S. Simon.

Application Serial No. 612,054, filed September 25, 1956, in the names of Helen P. Husek and Myron S. Simon. Application Serial No. 612,055, filed September 25, 6,

in the name of Helen P. Husek.

Application Serial No. 755,804, filed August 18, 1958, in the names of Elkan" R. Blout, Saul G. Cohen, Milton Green and Myron S. Simon.

Application Serial No. 824,785, filed July 3, 1959, in the names of Elkan R. Blout, Marilyn R. Cohler, Milton Green, Myron S. Simon and Robert B. Woodward.

Application Serial No. 849,727, filed October 30, 1959, in the names of Elkan R. Blout and Myron S. Simon.

Applications Serial Nos. 1,442 and 1,443, both filed I anuary 11, 1960, in the names of Elkan R. Blout, Saul 6. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. Woodward.

In color diffusion transfer processes, employing dye developers, a latent silver halide image in a photosensitive element is developed in the presence of the dye developer and, as a result of this development, the dye developer in the exposedareas is oxidized and substantially immobilized. At least a portion of the immobilization is believed to be at least due, in part, to a change in the solubility characteristics of the dye developer upon oxidation and especially as regards its solubility in alkaline solutions. In unexposed and partially expoised areas of the emulsion, the dye developer is unreacted and diffusible, and thus provides an imagewise distribution of unoxidized dye developer, dissolved in the liquid processing composition, as a function of the pointto-point degree of exposure of the silver halide emulsion.

s n-sass spaaeae 1 thedeveloped image.

The novel image-receiving elements within the scope of this invention may be prepared by coating a sheet of a suitable film support such as cellulose acetate, cellulose acetate-coated baryta paper,.etc'., which may be suitably subcoated forproper adhesion, with a solution, preferably a 3 to solution, comprising the pyridine acetal polymer. Acid-Water solutions may be used as solvents for the coating solutions. The coating and drying operations involved may be carried out by methods commonly employed in the art. The pyridine acetal polymers may comprise the sole dyeable film-forming material in the image-receiving layer or it may be added to other imagereceiving materials, e.g., gelatin, polyvinyl alcohol, etc. Especially useful results have been obtained when they were used in combination with polyvinyl alcohol. When the vacetals of this invention are used in combination with other image-receiving materials the ratio of the acetal polymer to the other image-receiving materials may be varied to suit particular needs; Especially good results have been obtained if the acetal polymers of this invention comprise 10 to 100% of the dyeable film-forming materials.

The acetals for use in this invention may be prepared by condensing polyvinyl alcohol with 4-pyridine carboxaldehydes in the presence of a suitable condensation catalyst, such, for example, as sulfuric acid, phosphoric acid, toluene sulfonic acid, etc. Suitable polyvinyl alcohols, for use in the preparation, maybe selected from the low, medium andv high viscosity, partially and completely hydrolyzed polymers which are commercially available. As examples of such polymers, mention may be made of Elvanol 70-05 (low viscosity, completely hydrolyzed), Elvanol 52-22 (medium viscosity, about 86 to 89% hydrolyzed) (trade names of E. I. du Pont de Nemours & Co., Wilmington, Delaware) andGelvatol 2-75 (trade name of Shawinigan Products Corp., New York, N.Y., for high viscosity, completely hydrolyzed polyvinyl alcohol). The degree of acetalization usually may be varied to suit particular needs; however, polymers having between about 10% to 50% of the hydroxy groups acetalized and especially those having about of, the hydroxyl groups acetalized have been found to be particularly useful.

The following nonlimitin'g examples illustrate the preparation of polymers for use in this invention.

Example 1 22 g. (0.5 m.) of Elvanol 70-05, 26.75 g. (0.25 m.) of 4-pyridine carboxaldehyde and 100 ml. of glacial acetic acid were mixed under nitrogen at 60 C. After a few minutes 10 g. of 85% phosphoric acid in 50 ml. of glacial acetic acid was added. Another 100 ml. of glacial acetic acid were added and the mixture was stirred overnight at 60 C. The resulting solution was poured into acetone to precipitate the polymer. The polymer was purified by reprecipitation twice frommethanol-water into water and once from methanol-water into isopropanol. After drying under vacuum at 45 C., 13 gms. of polymer were obtained. An elemental analysis indic-ated that the polymer contained 3.4% nitrogen. An infrared spectrographic analysis indicated that there was a small amount of esteri- .fication due to the presence of the glacial acetic acid in the synthesis.

Example 2 30.8 g. (0.7 m.) of Gelvatol 2-75 was dissolved in 200 ml. of water. 37.5 g. (0.35 m.) of 4-pyridine carboxaldehyde (neutralized with 34.8 g. of concentrated hydrochloric acid) was added and the mixture was heated under nitrogen to 60 C. with stirring. 3 ml. of concentrated sulfuric acid in 3 ml. of water was added and heating was continued at 60 C. overnight. The polymer was isolated by precipitation into 2% sodium hydroxide. The isolated polymer was reprecipitated from methanol-water into 2% sodium hydroxide and twice from methanolwater into water. Upon drying under vacuum at 45 C., 35 g. of dry polymer were obtained. An elemental analysis of the polymer gave a nitrogen content of 3.6%, indicating that 29.4% of the hydroxyl groups were acetalized.

The following nonlimiting examples illustrate the preparation of image-receiving elements within the scope of this invention.

Example 3 A sheet of subcoated baryta paper was coated with a water, ,B-methoxyethanol and methanol solution (5 to 1 to 2 by volume) containing a small amount of acetic acid and comprising:

Example 4 A sheet of subcoated baryta paper was coated with an aqueous coating solution comprising:

Percent Elvanol 72-60 2.4 Pyridine acetal of polyvinyl alcohol (Example 2)--- 2.4

Acetic acid (1 cc. per gram of the pyridine acetal). Sodium perborate 0.01 1-phenyl-5-mercaptotetrazole 0.08

and a few drops of a nonionic wetting agent.

Example 5 A control image-receiving sheet was prepared by coating a subcoated baryta paper with an aqueous'solution comprising:

Percent Elvanol 72-60 4.8 Sodium perborate 0.01 1-phenyl-5-mercaptotetrazole 0.08

and a few drops of a nonionic wetting agent.

The image-receiving elements prepared in the above examples, along with the polyvinyl alcohol control, were tested in diffusion transfer processes by using them in processes employing multilayer photosensitive elements prepared in a manner similar to that disclosed in the abovementioned copending application Serial No. 748,421. In general, the photosensitive elements comprised a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum; said emulsions having disposed in separate alkali-permeable layers behind them, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. The particular dye developers employed in the photosensitive elements were '(1) 1,4-bis-[methyl-,8-(2',5-dihydroxyphenyl)-ethylamino] -5,8-dihydroxyanthraquinone (a cyan.

red and blue light only, (3) red and green light only, (4)

totally exposed and (5) subjected to no exposure. After the transfer process, the integral densities in each of these areas were measured by reflectance using red, green and blue filters. The results, appearing in tabular form below,

indicate the improved density obtained using the imagereceiving elements of this invention.

'POLYVINYL ALCOHOL CONTROL OF EXAMPLE 5 Density Exposure Red Filter Green Filter Blue Filter Blue and Green 0. 99 0.53 0.45 Red and Blue 0.12 0. 60 0.44 Red and Green 0.08 0.18 0.68 Total Exposure 0.03 0.06 0.08 No Exposure.-- 1.09 1. 39 1.60

IMAGE-RECEIVING ELEMENT OF EXAMPLE 3 1.07 0.53 0. 38 0.11 0. 90 0.57 0.05 0.19 0.99 0.07 0.10 0.12 No Exposure 1.06 1.43 1. 51

IMAGE-RECEIVING ELEMENT OF EXAMPLE 4 Blue and Green 1. 04 0.50 0.41 0. 31 0. 94 0. 64 0.23 0.27 1.03 0.15 0.15 0.17 No Exposure 1. 04 1.37 1. 54

Percent Fading Filter Control I.R.E. of Example 3 Red 5 Gr n 24 0 Blue l 6 1 Image-receiving element.

It should be noted that in the preparation of the above image-receiving sheets a small amount of sodium perborate was used to harden the polyvinyl alcohol. The use of this material and other hardeners for polyvinyl alcohol are especially useful in reducing the water sensitivity of the image-receiving layers. They may be used when the pyridine acetals are used alone or when they are used in combination with polyvinyl alcohol.

The image-receiving elements of this invention are es pecially useful in composite film units intended for use in a Polaroid Land Camera, made by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of U.S. Patent No. 2,435,717, issued to Edwin H. 60

Land on February 10, 1948. In general, such composite film units comprise a photosensitive element, an imagereceiving element and a rupturable pod containing an aqueous alkaline processing solution. The elements and pod are so associated with each other that, upon process- 65 ing, the photosensitive element may be superposed on the image-receiving element and the pod may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such rolls are well known to the art. See, 70

for example, U.S. Patents Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

It is apparent that by selecting a film base from among suitable known opaque and transparent materials, reflection or transparent prints may be obtained.

It should be noted that other materials useful in the difiusion transfer processes may be incorporated into the image-receiving layer. As examples of such materials, mention may be made of dye mordants, anti-foggants, oxidizing agents, and acids and alkalies for pH adjustments.

Since certain changes may be made in the above prod nets and processes without departing from the scope of the invention herein involved, it is intended thatall matter contained in the-above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a photographic product for color diffusion transfer processes comprising a photosensitive element, includ ing at least one silver halide emulsion layer, a color-providing substance associated with said emulsion, said colorproviding substances being capable of forming an imagewise distribution of transferable color-providing substances as a function of development; an image-receiving element, including an image-receiving layer, and 'a rupturable container holding an aqueous alkaline processing solution; said photosensitive element and said image-receiving element being capable of being superposed on each other and said-container, being associated with said elements in such a manner that the container, upon being ruptured, is capable of releasing said processing solution between said superposed elements; the improvement of having said image-receiving layer comprise an acetal prepared by condensing polyvinyl alcohol with 4-pyridine carboxaldehyde.

2. A product as defined in claim 1 wherein said colorproviding substance is a dye developer.

3. A product as defined in claim 1 wherein between about 10% to of the hydroxyl groups of the polyvinyl alcohol are acetalized.

4. A product as defined in claim 3 wherein about 30% of the hydroxyl groups of the polyvinyl alcohol are acetalized.

5. A'product as defined in claim 1 wherein said image-receiving layer comprises polyvinyl alcohol in addition to said acetal.

6. A product as defined in claim 5 wherein the ratio of acetal to polyvinyl alcohol in said image-receiving layer is about 1 to 1 on a weight basis.

7. In a process of forming a photographic image in color wherein a latent image contained in an exposed silver halide emulsion is developed to provide an image wise distribution of color-providing materials in said emulsion and said imagewise distribution of color-providing materials is transferred by an alkaline aqueous processing solution to a superposed image-receiving layer to impart to said image-receiving layer a positive colored image, the step of transferring said imagewise distribution of color-providing materials to an image-receiving layer comprising an acetal prepared by condensing polyvinyl alcohol with 4-pyridine carboxaldehyde.

8. A process as defined in claim 7 wherein between about 10% to 50% of the hydroxyl groups of the polyvinyl alcohol are acetalized.

9. A process as defined in claim 8 wherein about 30% of the hydroxyl groups of the polyvinyl alcohol are acetalized.

10. A process as defined in claim 7 wherein said image-receiving layer comprises polyvinyl alcohol in addition to said acetal.

11. A process as defined in claim 10 wherein the ratio of acetal to polyvinyl alcohol in said image-receiving layer is about 1 to 1 on a weight basis.

12. In a process of forming a photographic image in color, wherein a latent image contained in an exposed silver halide emulsion is developed in the presence of a dye developer to provide in said emulsion a predetermined distribution of unoxidized dye developer and wherein at least a portion of said distribution of said unoxidized dye developer is transfenred by imbibition from 'said emulsion to an image-receiving layer in superposed receiving layer a reversed positive dye image of the developed image, the step of transferring said distribution of unoxidized' dye developer to an image-receiving layer comprising an acetal prepared by condensing polyvinyl alcohol with 4-pyridine carboxaldeh'yde.

13. A process as defined in claim 12 wherein between about 10% to 50% of the hydroxyl groups of the polyvinyl alcohol are acetalized.

14. A process as defined in claim 13 wherein about 30% of the hydroxyl groups of the polyvinyl alcohol are age-receiving 1ayer comprises polyvinyl alcohol in addition to said acetal.

16. A process as defined in claim 15 wherein the ratio f acetal to polyvinyl alcohol in said image-receiving layer is about 1 to 1 on a weight basis.

17. A process as defined in claim 12 wherein said dye developer is an azo dye developer.

18. A process as defined in claim 12 wherein said dye developer is an anthraquinone dye developer.

References Cited in the file of this patent UNITED STATES PATENTS 2,909,430 Rogers Oct. 20, 1959 

1. IN A PHOTOGRAPHIC PRODUCT FOR COLOR DIFFUSION TRANSFER PROCESSES COMPRISING A PHOTOSENSITIVE ELEMENT, INCLUDING AT LEAST ONE SILVER HALIDE EMULSION LAYER, A COLOR-PROVIDING SUBSTANCES ASSOCIATED WITH SAID EMULSION, SAID COLORPROVIDING SUBSTANCES BEING CAPABLE OF FORMING AN IMAGEWISE DISTRIBUTION OF TRANSFERABLE COLOR-PROVIDING SUBSTANCES AS A FUNCTION OF DEVELOPMENT; AN IMAGE-RECEIVING ELEMENT INCLUDING AN IMAGE-RECEIVING LAYER AND A RUPUTURABLE CONTAINER HOLDING AN AQUEOUS ALKALINE PROCESSING SOLUTION SAID PHSOTOSENSITIVE ELEMENT AND SAID IMAGE-RECEIVING ELEMENT BEING CAPABLE OF BEING SUPERPOSED ON EACH OTHER AND SAID CONTAINER BEING ASSOCIATED WITH SAID ELEMENTS IN SUCH A MANNER THAT THE CONTAINER UPON BEING RUPTURED IS CAPABLE OF RELEASING SAID PROCESSING SOLUTION BETWEEN SAID SUPERPOSED ELEMENTS; THE IMPROVEMENT OF HAVING SAID IMAGE-RECEIVING LAYER COMPRISES AN ACETAL PREPARED BY CONDENSING POLYVINYL ALCOHOL WITH 4-PTRIDINE CARBOXALDEHYDE 